The present invention relates to an image pickup system and particularly relates to an image pickup system for reading an image signal from an arbitrary area of all image pickup areas of a photographed body.
A solid-state image pickup device described in Jpn. Pat. Appln. KOKAI Publication No. 56-102172 is conventionally known as the image pickup system of this kind.
Namely, the solid-state image pickup device described in JPN. Pat. Appln. KOKAI Publication No. 56-102172 partially scans an individual pixel constituting a solid-state image pickup element, and reads only an image signal of each pixel in a small area required in all image pickup areas of the solid-state image pickup element, without any blanking period so that only the image signal in the small area is read continuously and repeatedly.
In the conventional example, the image pickup device of a so-called X-Y address system reads a signal generated in each pixel while it sequentially scans the individual pixel constituting the image pickup element. In the image pickup device, a time from reading of the image signal of a certain pixel to the next reading of the image signal of the pixel becomes a substantial signal accumulating time. Thus, a level of the image signal read from each pixel of the image pickup element is determined.
Accordingly, when only the image signal of each pixel in the required small area in all the image pickup areas is read repeatedly and continuously, the number of read pixels is small in comparison with a case in which the image signal of each pixel is read from all the image pickup areas. Accordingly, the signal accumulating time is shortened. The image signal at a proper level is obtained when the image signal is read from all the image pickup areas. However, a problem exists in that no image signal at the proper level is obtained from the small area. However, this problem is not considered in the conventional solid-state image pickup device.
In consideration of the problem, an object of the invention is to provide an image pickup system in which an image signal at a proper level with high definition can be also simply obtained from an arbitrary small area selected from all image pickup areas.
To achieve the object, a first aspect of the invention provides an image pickup system comprising a photographing lens for focusing and forming incident light from a photographed body as an image on an image pickup face; an image pickup element for photoelectrically converting the incident light focused and formed as an image by the photographing lens and converting the incident light to an image signal; first control means for obtaining a first image signal by reading the image signal from each of pixels of a first area in all image pickup areas of the image pickup element; second control means for obtaining a second image signal by reading the image signal from each of pixels of a second area smaller than the first area in all the image pickup areas of the image pickup element; display means for displaying the first image signal obtained by the first control means; and third control means for controlling a level of the first image signal obtained by the first control means and a level of the second image signal obtained by the second control means such that these levels are substantially equal to each other.
Furthermore, the third control means for controlling the levels of the first and second image signals to be substantially equal to each other includes a digital processing means or an analog processing means as described later on.
A second aspect of the invention provides an image pickup system comprising a photographing lens for focusing and forming incident light from a photographed body as an image on an image pickup face; an image pickup element for photoelectrically converting the incident light focused and formed as an image by the photographing lens and converting the incident light to an image signal; first control means for obtaining a first image signal by reading the image signal from each of pixels of a first area in all image pickup areas of the image pickup element; second control means for obtaining a second image signal by reading the image signal from each of pixels of a second area smaller than the first area in all the image pickup areas of the image pickup element; display means for displaying the first image signal obtained by the first control means; and third control means for controlling the total number of pixels as reading objects in the first area in all the image pickup areas of the image pickup element and the total number of pixels as reading objects in the second area such that these total numbers are substantially equal to each other.
A third aspect of the invention provides an image pickup system comprising a photographing lens for focusing and forming incident light from a photographed body as an image on an image pickup face; an image pickup element for photoelectrically converting the incident light focused and formed as an image by the photographing lens and converting the incident light to an image signal; first control means for obtaining a first image signal by reading the image signal from each of pixels of a first area in all image pickup areas of the image pickup element; second control means for obtaining a second image signal by reading the image signal from each of pixels of a second area smaller than the first area in all the image pickup areas of the image pickup element; display means for displaying the first image signal obtained by the first control means; and gain adjusting means for adjusting a gain of the image signal read from the second area in accordance with a ratio of the total number of pixels as reading objects in the first area in all the image pickup areas of the image pickup element and the total number of pixels as reading objects in the second area.
Namely, the second aspect of the invention. provides the image pickup system having the third control means for setting the total number of pixels as reading objects in the first area and the total number of pixels as reading objects in the second area such that these total numbers are substantially equal to each other. This third control means in the second aspect is provided as a concrete means of the third control means for setting the levels of the first and second image signals to be substantially equal to each other in the first aspect of the invention.
Further, the third aspect of the invention provides the image pickup system having the gain adjusting means for adjusting a gain of the image signal read from the second area in accordance with a ratio of the total number of pixels as reading objects in the first area and the total number of pixels as reading objects in the second area. The gain adjusting means in the third aspect of the invention is provided as a concrete means of the third control means for setting the levels of the first and second image signals to be substantially equal to each other in the first aspect of the invention.
A fourth aspect of the invention provides the image signal is read from the first area by thinning-out the image signal, and the image signal is sequentially read from the second area without thinning-out the image signal. The fourth aspect of the invention is provided as a concrete means of the first and second control means in the first to third aspects of the invention.
Further, according to a fifth aspects of the invention, image signals of predetermined plural pixels from respective areas partitioned at predetermined intervals in horizontal and vertical directions in the first area are added and read. The fifth aspects of the invention is provided as a concrete means of the first control means in the first to third inventions.
In the explanation, the first area includes a case in which the first area is all image pickup areas.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.